We consider an IoT network that consists of multiple EH sensors, a cache-enabled edge node, and multiple users. Users are interested in timely information about physical quantities (e.g., speed or temperature), each measured by a sensor. Users send requests to the edge node which maintains the most recently received measurements from each sensor. To serve a user's request, the edge node either commands the sensor to send a fresh status update or uses the aged measurement from the cache.
This imposes a trade-off between the information freshness and the energy status of the sensors' batteries, creating challenges to the design of an AoI-aware status update control policy herein.
Due to the limited amount of radio resources (e.g., bandwidth) in an IoT network, we consider that only a portion
of sensors can send status updates
at each slot, imposing a per-slot transmission constraint.
Furthermore, in contrast to the prior works (e.g., [1]}, [2]}, [3]}), we consider a practical scenario where the edge node is informed of the sensors' battery levels only via received status updates, giving rise to partial battery knowledge at the edge node.
